data: increased file clearing performance

This change passes all file node ids for clearing to the sqlite storage at once and makes use of ON DELETE CASCADE for
everything else, instead of manally deleting all source locations.

src/lib/data/SqliteStorage.cpp

@@ -160,13 +160,6 @@ void SqliteStorage::removeNameHierarchyElement(Id id)
 	).c_str());
 }
 
-void SqliteStorage::removeElementsWithLocationInFile(Id fileId)
-{
-	m_database.execDML((
-		"DELETE FROM element WHERE id IN (SELECT element_id FROM source_location WHERE source_location.file_node_id == " + std::to_string(fileId) + ");"
-	).c_str());
-}
-
 void SqliteStorage::removeFile(Id id)
 {
 	if (isFile(id))
@@ -181,6 +174,13 @@ void SqliteStorage::removeFile(Id id)
 	}
 }
 
+void SqliteStorage::removeFiles(const std::vector<Id>& fileIds)
+{
+	m_database.execDML((
+		"DELETE FROM element WHERE id IN (" + utility::join(utility::toStrings(fileIds), ',') + ");"
+	).c_str());
+}
+
 void SqliteStorage::removeUnusedNameHierarchyElements()
 {
 	m_database.execDML(